A wrapping method with a film includes various kinds of wrapping methods utilizing the characteristics of each film, such as a method of sealing in a bag form, an overlapping method, a stretch wrapping method, a spin packing method, etc. Further, a single layer film mainly using an ordinary resin such as polyethylene, polypropylene, polyvinyl chloride, etc., are generally used as the film used for these methods. However, with the increase of the level required for the wrapping film, the variety of the wrapping film, and the change of the social needs, the cases that these films cannot deal with are increased.
For example, foods such as fruits, fresh fishes, fresh meats, vegitables, etc., are directly placed on a plastic tray, and a vinyl chloride resin film is, hitherto, mainly used as a film for stretch wrapping these foods. Recently, from the problem of a safety hygiene property and the increase of the consciousness for the earth environment, the development has been actively carried out on using the films of an ethylene resin such as a low-density polyethylene resin, an ethylene-vinyl acetate copolymer, etc., causing less problems of safety hygiene and environmental pollution in place of the conventional polyvinyl chloride.
However, in the case of using a low-density polyethylene resin, etc., alone, it was impossible to simultaneously satisfy the desired self-adhesive property, the low-temperature heat sealing property, and the flexibility of a film. Further, in an ethylene-vinyl acetate copolymer resin film, by properly selecting the content of vinyl acetate, the molecular weight of the copolymer, etc., the problem in the case of using the low-density polyethylene resin film described above could be solved to some extent, but when the corner of the tray was sharp or foods having a sharp site were packed, a problem occurred that the film was broken as being teared.
Thus, the inventors previously proposed a wrapping multilayer film aiming at simultaneously meeting the necessary properties by combining an ethylene polymer layer and a propylene copolmer layer as described in the specifications of Japanese Patent Application Nos. 4-195210, 5-150366, 5-150367, 5-150368, and 4-195214.
However, although for producing such a multilayer film economically with a good efficiency, it is effective to additionally dispose, for example, a recycled resin layer containing trimming losses, etc., formed at the production of the films, there is a problem that the film is whitened at heat-sealing the film according to the manner of disposing the recycled resin layer.